A human heart includes four heart valves that determine the pathway of blood flow through the heart: the mitral valve, the tricuspid valve, the aortic valve, and the pulmonary valve. The mitral and tricuspid valves are atrioventricular valves, which are between the atria and the ventricles, while the aortic and pulmonary valves are semilunar valves, which are in the arteries leaving the heart. Ideally, native leaflets of a heart valve move apart from each other when the valve is in an open position, and meet or “coapt” when the valve is in a closed position. Problems that may develop with valves include stenosis in which a valve does not open properly, and/or insufficiency or regurgitation in which a valve does not close properly. Stenosis and insufficiency may occur concomitantly in the same valve. The effects of valvular dysfunction vary, with regurgitation or backflow typically having relatively severe physiological consequences to the patient.
Recently, flexible prosthetic valves supported by stent or scaffold structures that can be delivered percutaneously using a catheter-based delivery system have been developed for heart and venous valve replacement. These prosthetic valves may include either self-expanding or balloon-expandable stent structures with valve leaflets attached to the interior of the stent structure. The prosthetic valve can be reduced in diameter, by compressing onto a balloon catheter or by being contained within a sheath component of a delivery system, and advanced through the venous or arterial vasculature. Once the prosthetic valve is positioned at the treatment site, for instance within an incompetent native valve, the stent structure may be expanded to hold the prosthetic valve firmly in place. One example of a stented prosthetic valve is disclosed in U.S. Pat. No. 5,957,949 to Leonhardt et al. entitled “Percutaneous Placement Valve Stent”, which is incorporated by reference herein in its entirety. Another example of a stented prosthetic valve for a percutaneous pulmonary valve replacement procedure is described in U.S. Patent Application Publication No. 2003/0199971 A1 and U.S. Pat. No. 8,721,713, both filed by Tower et al., each of which is incorporated by reference herein in its entirety.
Although transcatheter delivery methods have provided safer and less invasive methods for replacing a defective native heart valve, complications may arise including vessel trauma due to percutaneous delivery within highly curved anatomy and/or due to a large delivery profile of the prosthesis, inaccurate placement of the valve prosthesis, conduction disturbances, coronary artery obstruction, and/or undesirable paravalvular leakage and/or regurgitation at the implantation site. More particularly, for example, a prosthesis that is positioned too deep relative to the native annulus or placed unevenly within the native annulus in terms of depth may cause conduction disturbances. In another example, if a prosthesis is not circumferentially centered relative to the native annulus, the deployed prosthesis may dislodge from the implantation site and/or undesirable paravalvular leakage and/or regurgitation may occur. Thus, it is imperative that the prosthesis be accurately located relative to the native annulus prior to full deployment of the prosthesis.
Embodiments hereof are directed to a delivery system for a transcatheter valve prosthesis having an integral centering mechanism for positioning a valve prosthesis in situ to address one or more of the afore-mentioned complications.